Seville in southern Spain is well known for the bright oranges that are dotted across its 48,000 trees in spring. A draw for tourists, Seville's trees create 5,700 tonnes (5.7 million kg) of the attractive fruit, and while some oranges are shipped to the UK to go into marmalade, or used to create liqueurs such as Cointreau and Grand Marnier, most are left to rot. By winter the city's oranges are causing havoc as they fall onto paths and roads, and the local government has to employ around 200 people to clear them up. But now the city's fruit is set to be used to generate electricity. Click or scroll on to find out how...

So how will the unwanted oranges be used to create electricity? The methane that the fruit emits as it rots will be used to power a generator. Initially this clean electricity will be used to run one of the city’s water purification plants as Emasesa, the municipal water company, is leading the scheme. This will use about 35 tonnes (35,000kg) of the 15,000 tonnes (15 million kg) of oranges produced across southern Spain every year, but if the trial goes well Emasesa wants to use all of the unwanted fruit to create electricity in future. Click or scroll on to discover how much electricity Seville's oranges can create...

Initial tests have shown that 1 tonne (1,000kg) of oranges can produce 50kWh of electricity, enough to power five homes for one day. It's predicted that, if all of the city's oranges were used, as many as 73,000 homes could be provided with electricity. And it seems that oranges are a particularly good electricity generator as their "juice is fructose [and] made up of very short carbon chains and the energetic performance of these carbon chains during the fermentation process is very high", according to Benigno López, head of Emasesa's environmental department.

Using unwanted oranges to create clean electricity is an innovation that could help to reduce pollution, but it's by no means the only exciting recent development. From COVID-19 and climate change to pollution and food supplies, click or scroll through to discover the innovations that could solve some of the world's biggest current problems..

As COVID-19 can linger on certain surfaces for days, scientists have been scrambling to create potent antiviral coatings. A spray developed by the Hong Kong University of Science and Technology (HKUST) last April uses heat-sensitive polymers that release disinfectants on human contact and can offer protection for up to 90 days. Meanwhile, researchers at Israel's Ben-Gurion University of the Negev revealed that they were working on a similar nano-metal and polymer-based coating in May last year, which they want to be effective for months at a time.

Elsewhere, German start-up UVIS has invented a virus-killing UV light box that disinfects escalator handrails, leaving them 99.99% germ-free. Called ESCALITE, the product has already been snapped up by some of the world's leading escalator companies and, like the aforementioned coatings, could play a major role in preventing the spread of COVID-19 and other infectious agents.

Another UV light-based bacteria buster is this LED Desktop Disinfection Light, which sits between a computer screen and keyboard and automatically blasts the keys with UV light every hour to rid it of mould, bacteria, fungus and viruses. Each cleanse takes five minutes and motion sensors ensure the light only comes on when users aren’t using the keyboard to prevent potentially harmful UV exposure. Produced by accessory manufacturer Targus, the company plans to start selling the devices for $299 (£220) from April. It is also working on an antimicrobial mouse and keyboards.

And now onto germs of a good kind. Psychobiotics are a type of live bacteria (probiotics and prebiotics) that could have mental health benefits when ingested because of the way they interact with bacteria in the gut. Knowledge of the exact impact the bacteria can have is limited, but recent studies on volunteers showed evidence that those who had consumed them were less likely to say they were in a bad mood or feeling distressed than those who were given a placebo, suggesting that psychobiotics could be used to help those with depression or anxiety in the future. Lots more research needs to be done in the field, but scientists are excited by the prospect of bacteria-brain relationships.

No longer the stuff of science fiction, Minority Report-style touchless gesture recognition is being fine-tuned by a host of major organisations, from tech titans such as Apple and Microsoft to research universities, with COVID-19 accelerating its widespread adoption. By way of example, Abu Dhabi Airport installed the technology in 53 lifts in June 2020 to help minimise the spread of the virus, and the trend soon caught on. In July, Norwegian airport operator Avinor partnered with tech company Amadeus to launch touchless travel across four airports, covering everything from check-in and baggage drop to security and boarding.

The plastic waste crisis is one of the biggest challenges humanity is grappling with. Though the science is in its early stages, researchers around the world are coming up with all sorts of novel solutions. Among the most promising are bio-engineered bugs that munch their way through waste polymers, swiftly breaking them down into monomers that can be recycled easily.

Now read about the countries where the world's waste goes

In a similar vein, scientists have developed technologies that transform waste plastic into clean, low-sulphur fuels, and the market for these plastic-derived fuels is set to grow significantly in the coming years. Major players in this emerging field include Plastic2Oil, Enexor BioEnergy, Agilyx Corporation and PowerHouse Energy.

Just as with Seville's wasted oranges, every year around a third of all food produced – a staggering 1.3 billion tonnes – is lost or wasted, with much of it ending up on landfill. Fortunately, scientists have been working diligently on technologies that can convert that waste to fuel. Notable examples include Cornell University's two-step bio-oil process and the HomeBiogas System, which uses bacteria to convert food scraps into biogas.

The world's population is set to grow by two billion people by 2050, according to the UN, and that means that we will need as much as 70% more food. Therefore new farming methods that take up less space will be necessary. Urban vertical farming, where large warehouses within cities and towns are used to grow crops in stacked layers, is already happening. But other solutions that won't take up any land at all include a floating farm proposed by Barcelona's Forward Thinking Architecture, which would grow crops that wouldn't require fertilisers, pesticides or rainwater, as well as farming fish sustainably. 

Climate change is one of the greatest threats the world faces today. As the planet's oceans heat up, scientists are racing to develop technologies to try to reverse the process. Last April a new method of shading and cooling Australia's Great Barrier Reef was successfully trialled, and has given scientists some hope. Headed by oceanographer Daniel Harrison, researchers from Australia's Southern Cross University sprayed trillions of salt particles into the air over the reef to form cloud droplets that reflect sunlight. This in turn cooled the water and protected the reef's corals from bleaching.

It's not just the oceans that global warming is affecting, but the air we breathe too. So how amazing would it be if we could deploy huge vacuums that could literally suck carbon from the air to help reverse climate change? The good news is this technology has already been developed. Leading the way is Canadian firm Carbon Engineering, which is backed by Bill Gates and oil giants such as Chevron and BHP. The firm is using giant fans, combined with complex chemical processes, to extract the greenhouse gas from the air. Another start-up testing the technology is Switzerland-based Climeworks, which started construction on its new capture and storage plant at the beginning of December. However, currently it is very expensive, costing $200 (£160) to extract a tonne of carbon dioxide. 

Now read about Bill Gates's predictions for the world's next break-throughs

Scientists are also looking at ways air conditioning units could be engineered to pull carbon dioxide out of the air and even convert the offending gas into fuel. These energy-intensive devices could then help reverse climate change rather than contribute to it. Though the technology is still some way off, in 2019 a team from Germany’s Karlsruhe Institute of Technology showed that it is actually feasible.

Wearable air conditioners within our clothes could help us cope better with heatwaves and reduce the number of fatalities. In July 2020 Sony launched the Reon Pocket, a wearable cooling device that fits snugly in specially-designed shirts and T-shirts and can cool the surface of the skin by as much as 13°C (23°F). Only available in Japan at the moment, as it was set to be launched in conjunction with the now-postponed Tokyo Olympic Games, it retails for around $120 (£90).

Discover The cost of cancelling 2020's mega-events

Nine out of 10 people around the world breathe polluted air, which accounts for seven million deaths a year according to the World Health Organization (WHO). Dutch inventor Daan Roosegaarde has come to the rescue with his giant air purifier. The seven metre-tall smog-busting machine, which can clean 30,000 ug/m3 of air per hour, has already been installed at sites in the Netherlands, Poland, China and South Korea, and is part of the Smog Free Project to reduce air pollution.

The coronavirus pandemic means most of us are used to wearing masks in shops and enclosed public spaces. But air wearables company AirPop has gone above and beyond the humble face mask and produced what is essentially a fitness tracker for lungs. The Active+ Halo Smart Mask tracks breathing, air quality and the mask filter’s effectiveness via an app, while promising protection from pathogens such as coronavirus, airborne risks including dust storms, and man-made pollution such as factory pollution. While demand for face masks has soared because of the COVID-19 outbreak, AirPop actually came about six years ago when founder Chris Hosmer wanted to design a mask for his young daughter, who was suffering from acute respiratory reactions.

Developed by engineers in Switzerland, Solar Impulse 2 made history in 2016 when it completed the first round-the-world flight by a solar-powered aeroplane. The project's founders have predicted that solar-powered planes carrying up to 50 passengers could take to the skies for short-haul flights as soon as 2026, though many experts are sceptical about the technology's future prospects. In 2019 the solar-powered plane was sold onto a small start-up called Skydweller, which plans to develop the technology for military use, according to an investigation by Swiss television network RTS.

Renewables will supply 40% of our energy demands in 2040, predicts the International Energy Agency (IEA), up from 25% today. But storing and bringing these clean energies into national grids is a growing problem. Renewable energy threatens to overwhelm existing energy grids, a system currently focused on big, centralised power plants that feed energy down transmission lines and then into local distribution substations in a top-down one-way approach. This antiquated method struggles to incorporate renewables as they typically don't generate energy at a consistent rate, and they often come from localised sources such as solar panels and batteries. And so engineers are working on so-called Autonomous Energy Grids (AEGs): decentralised, bottom-up alternatives that should also help protect against and contain outages caused by everything from cyber attacks to natural disasters.

Now read: The world could soon run on 100% renewables. Once it's solved this problem

The AuREUS system is a technology that absorbs stray UV light from sunlight and converts it into clean, renewable electricity. That electricity can then be used, for example to charge batteries, or stored. The plastic on which the system is based is made from upcycled crop waste taken from farms hit by natural disasters, which helped the project to secure the first James Dyson Award for sustainability in 2020. The next step for the project is to source all its dyes naturally – the material is available in red, orange, yellow, green and blue, but the blue colouring is still chemical-based – and to increase its current capacity.

The world is facing an antibiotic apocalypse as antimicrobial resistance increases, and the COVID-19 pandemic, which has resulted in a surge in antibiotic use to treat secondary infections and complications, is accelerating the process. New antibiotics are desperately needed and scientists are increasingly turning to artificial intelligence to develop them. By using a machine-learning algorithm, MIT researchers were able to identify a powerful new antibiotic that can kill antiobiotic-resistant bacteria.

In the near future, 3D printing is set to revolutionise organ transplants and prosthetics. In 2019, researchers at Israel's Tel Aviv University created the world's first 3D-printed heart using a patient's own cells and other biological materials, eliminating the risk of implant rejection. Scientists have also developed 3D-printed corneas, bone matrices and cartilage derived from stem cells, as well as 3D-printed skin cells. There are always new developments in this exciting field, and 3D printing is also being implemented to create increasingly realistic models of organs for training purposes.

And it's not just medicine that 3D printing could benefit. The latest printing technique could be used to print food, ridding the world of food insecurity and mitigating global warming. According to the experts, the technology massively decreases food waste, cuts costs and streamlines supply chains, while 3D-printed meat, which has already arrived, could significantly reduce our reliance on livestock farming, which is a major contributor to global heating.

Researchers the world over are developing temporary smart tattoos that could warn you if you are unwell. The tattoos would feature special dyes that react to changes within and outside of the body, enabling the wearer to monitor their blood pressure, keeps tabs on blood sugar, track their exposure to the sun, and more. Researchers at Microsoft have even invented a smart tattoo that can be used as a remote control using Bluetooth, while Google is developing SkinMarks, which respond to swiping or tapping in the same way that a smartphone would.

A computer chip that can be implanted in the brain to replace damaged neurons sounds like something out of a science fiction novel, but the technology has already been invented by researchers at the Universities of Bath, Zurich and Auckland. Elon Musk also unveiled Gertrude the pig in August 2020, who had been living with a tiny computer in her brain as part of the billionaire’s Neuralink trials. It is thought that the innovation could have the potential to transform the treatment of heart failure, spinal cord injuries, Alzheimer's and other neurological disorders.

Yet another science fiction-worthy innovation, in late 2019 doctors at the University of Maryland Medical Center in Baltimore placed humans in suspended animation for the first time by replacing all their blood with ice-cold saline solution. This remarkable process, which is officially called emergency preservation and resuscitation (EPR), enables physicians to suspend time, and take hours to treat traumatic injuries that would otherwise kill the patient in a matter of minutes. The technique could save countless lives in the future.

Virtual reality has taken off in a big way, but lacks realism as it relies solely on sound and vision to create artificial worlds. Scientists are now developing tactile virtual reality to create truly immersive experiences. Notable examples of the emerging technology, which could revolutionise not just entertainment but even medicine, include a synthetic skin invented by researchers at Northwestern University. Users wear the sheet-like material, which uses programmed, vibrating actuators to allow you to 'feel' the hand of another user across the world, or the 'touch' of a medical professional as they treat you online.

As the world heats up, wildfires are increasing in intensity and frequency. Fighting these fires is becoming ever more challenging but scientists are rising to the challenge with an amazing new technology: the sonic fire extinguisher. First developed in 2015 by two engineering students at Virginia's Mason University, the acoustic extinguisher, which can be installed on a drone, works by using sound waves to separate oxygen from the fuel source, thus putting out the blaze.

Imagine if you could fully charge your electric car in the same time it takes to fill up a conventional vehicle with petrol? Superfast-charging lithium-ion batteries are being developed by companies around the world including Tesla, Enevate and StoreDot, with the technology likely to go mainstream in the not-too-distant future. Research at the University of Science and Technology of China suggests that its version of the battery could provide electric cars with a range of 500km (310 miles) after just 10 minutes of charging, which has been described as the “holy grail” of batteries.

Still, the mining of lithium for these batteries isn't great for the environment and they also rely on cobalt, which is expensive and linked to human rights abuses in countries such as the Democratic Republic of the Congo. Thankfully, scientists are working on alternatives, the most promising of which are based on salt, an altogether greener and more cost-effective option. At the moment sodium batteries don’t perform as well as those made with lithium, but recently a prototype in South Korea handled around 500 complete charging cycles before capacity dropped to 80%, according to a publication released in May 2020, which is promising progress.

Batteries might be an obvious place to cut emissions, but how about car tyres? As the wheels of a vehicle become worn, they shed microplastics, which are then released into the atmosphere – a typical London bus produces 336g of tyre wear each day, an amount similar in size to a grapefruit. Technology designed by The Tyre Collective attaches to the wheel and captures 60% of the rubber fragments before they are able to pollute the environment, and the creation was recognised with a James Dyson Award in 2020. The designers and engineers behind the project hope that their invention will contribute to vehicle operators' and manufacturers' ability to deliver a zero-emission future.

The holy grail of energy, nuclear fusion would produce abundant clean, carbon-free energy with zero long-lived nuclear waste and eliminate the risk of catastrophic meltdowns. Scientists have been chasing the technology for decades but are edging ever closer to a breakthrough. In fact, the ITER, the world's largest experimental fusion facility, is under construction in the South of France. A collaboration of 35 nations, the project aims to prove fusion power can be produced sustainably on an industrial scale.

Humanity's future survival may very well rest on our ability to colonise outer space. But before we even think about setting up home on other planets a multitude of challenges need to be overcome, including the development of toilets that can operate in different planetary gravities. To address this, NASA launched its Lunar Loo Challenge in June 2020, a competition to design a toilet that can work on the Moon. While space toilets do exist, they only work in microgravity, and the contest was looking for a smaller, more efficient option that works in both microgravity and lunar gravity. The competition closed in August and first place was awarded to THRONE, a toilet that incorporated a bladeless fan to draw in waste. Other designs commended by judges included a foldable dry toilet and a fully self-contained lunar toilet. 

Exploiting the asteroid belt for resources such as water and rare metals could be a catalyst for humans colonising other planets and help save the environment on Earth. Though the technology is in its infancy, Japanese spacecraft Hayabusa-2 successfully landed on an asteroid in 2018 and spent a year and a half taking samples. Its first full container of space rock landed in Australia on 5 December 2020 in “perfect” condition. The next stage of their investigation involves collecting samples from Mars’ largest moon, Phobos. NASA is also working on a spacecraft that will explore an asteroid called Psyche, which is thought to contain resources worth an incredible $10,000 quadrillion (£8,000 quadrillion).

Getting tested for breast cancer can be an uncomfortable and awkward process, and around 40% of women skip mammogram screenings, according to a study by America's Center for Disease Control and Prevention (CDC), which could lead to 33% of cancers being detected too late. This inspired engineer Judit Giró Benet to design The Blue Box, which can painlessly identify breast cancer in a home environment. Women place a urine sample in the box and chemical sensors will detect any breast cancer biomarkers. Users can then view the result on The Blue Box app. Benet’s project was the international winner of the James Dyson Award in 2020, and the company is now patenting its revolutionary technology and carrying out further testing.

Drones are quickly becoming a part of our day-to-day lives as photographers and hobbyists take them to beauty spots and big names such as Amazon are incorporating them into their delivery processes. But this new take on the drone, the Smellicopter, does a lot more than fly around. It can also seek out certain smells in its surroundings thanks to its live moth antenna, which is taken from an anaesthetised insect and then remains biologically and chemically active for up to four hours. It’s hoped that the Smellicopter, which has been created by researchers from the University of Washington, will be useful in the future in detecting chemicals in the air, identifying gas leaks and explosives and even locating disaster survivors. 

Now read more about the workers that can go where humans can't

Space-based solar power has been talked about since the 1960s, but the idea has only recently started to become a real possibility. In theory putting large solar farms in space means that solar cells will be able to collect the sun's energy 24 hours a day, without being affected by adverse weather conditions. NASA started researching the possibility in the late 1990s and pictured is a design for a solar power satellite. But key challenges such as how to assemble and deploy such solar farms remained, especially as one station may have to cover the equivalent of 1,400 football pitches, as well as how to transmit the energy back to Earth. But in recent years other agencies and countries have started to look into the prospect of harnessing the sun's power from space. In 2017, researchers at the California Institute of Technology revealed designs for a modular power station made up of thousands of very light solar cells, which would solve the size issue, and the University of Liverpool has explored how 3D printing could help to create fuel-free power stations. Meanwhile, researchers at the Japan Aerospace Exploration Agency have developed designs for antennae that could receive the energy from the space stations through electromagnetic fields. In 2019 China announced that it was building the world's first solar power station and hopes to have it operational by 2050.

Now discover why the world's cities will never look the same again